What? Now you’re spewing nonsense, or you’re just bad. It’s much more that 20%. I recorded a video of me fighting two elite mobs, first with a sword and board, and then with a 2H. I can solo them with a sword and board, but have to run for my life with the 2H. The increase in the damage taken is on the order of a magnitude, at least 10 times the damage is taken when fighting with the 2H compared to the sword and board. Video below:
How the heck are you only getting 20% damage reduction with a shield? Are you that bad?